Bio-floc Technology flocs; water from recirculating aquaculture system; gut and gill of BFT and RAS farmed fish Raw sequence reads. Bio-floc Technology flocs; water from recirculating aquaculture system; gut and gill of BFT and RAS farmed fish

Biological treatment is the main wastewater treatment method of this recirculating aquaculture system and biological flocculation system. Therefore, the research on microbial community in the system is of great significance for understanding the operating principle of the system, improving the operation mode of the system and improving the treatment efficiency.